1. Field of the Invention
The present invention relates, in general, to a tilt adjusting unit for steering columns and, more particularly, to a tilt adjusting unit for steering columns, which allows a user to easily confirm whether a steering column is locked at a desired angle or not.
2. Description of the Related Art
Generally, a steering column for vehicles couples a steering wheel to axles of wheels, and functions to change a moving direction of a vehicle. As a user rotates the steering wheel in a direction, the steering column rotates in the same direction to control directions of the wheels, thus adjusting the moving direction of the vehicle.
Further, the steering column is constructed to be tiltable up and down, so that a position of the steering wheel is adjusted according to a user's size or preference, by adjusting an angle of the steering column. A hinge shaft is provided on a mid-part or a lower end of the steering column so that the steering column rotates around the hinge shaft. Further, a tilt adjusting unit is provided at a predetermined position around the steering column to guide a tilting motion of the steering column and lock the steering column at an adjusted angle.
As shown in FIG. 1, a conventional tilt adjusting unit for steering columns includes a mounting bracket 1, first and second support brackets 3, and a movable bracket 4. The mounting bracket 1 is mounted to a predetermined portion of a vehicle body. The first and second support brackets 3 are mounted to the mounting bracket 1 to be placed on left and right sides of a steering column 2. The movable bracket 4 is placed at a position between the first and second support brackets 3, and is secured to the steering column 2, through, for example, a welding process, to tilt along with the steering column 2.
First and second support parts 5 are provided on left and right edges of the movable bracket 4 to be supported by inner surfaces of the first and second support brackets 3, respectively. Each of the first and second support parts 5 has a through hole 5a, and a guide slot 3a is formed through each of the first and second support brackets 3 at a position corresponding to the through hole 5a. The first and second support brackets 3 and the movable bracket 4 are connected to each other, by an adjusting bolt 6 which passes through the through holes 5a of the first and second support parts 5 and the guide slots 3a of the first and second support brackets 3.
Such a construction makes the adjusting bolt 6 move up and down along the guide slots 3a when the movable bracket 4 is angled vertically, thus adjusting the angle of the steering column 2 which is secured to the movable bracket 4.
Further, the adjusting bolt 6 includes a head 6a and a shank 6b. The head 6a is provided at an end of the adjusting bolt 6 to be supported by an outer surface of one of the first and second support brackets 3. The shank 6b extends from the head 6a, and passes through the first and second support brackets 3 and the first and second support parts 5 to be outwardly projected from a remaining one of the first and second brackets 3. An external threaded part 6c is formed on an end of the shank 6b which passes through the first and second support brackets 3. An adjusting nut 7 having an internal threaded part 7a engages with the external threaded part 6c of the adjusting bolt 6. Further, an adjusting lever 8 is fastened to the adjusting nut 7 using a screw 9.
Thus, when the angle of the steering column 2 is adjusted along the guide slots 3a, and the adjusting lever 8 rotates to tighten the adjusting nut 7, the adjusting nut 7 presses the first and second support brackets 3. At this time, friction between the first and second support brackets 3 and the movable bracket 4 increases, thus locking the steering column 2 at a desired angle.
Meanwhile, when the user desires to re-adjust the angle of the steering column 2 in such a state, the adjusting lever 8 rotates in a reverse direction to loosen the adjusting nut 7. At this time, the friction between the first and second support brackets 3 and the movable bracket 4 reduces, thus allowing the angle of the steering column 2 to be adjusted again.
As such, the conventional tilt adjusting unit for steering columns is constructed to lock the steering column 2 using the adjusting nut 7. In this case, as the adjusting nut 7 is increasingly tightened, friction between the first and second support brackets 3 and the movable bracket 4 gradually increases. Thus, the conventional tilt adjusting unit has a problem in that it is difficult to determine an extent to tighten the adjusting nut 7 so as to reliably lock the steering column 2 at a desired angle.